Dental filling material

ABSTRACT

An dental filling material comprising a thermoplastic polymer. The thermoplastic polymer may be biodegradable. A bioactive substance may also be included in the filling material. The thermoplastic polymer acts as a matrix for the bioactive substance. The composition may include other polymeric resins, fillers, plasticizers and other additives typically used in dental materials. The filling material is used for the filing of root canals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.10/279,609 filed Oct. 24, 2002, which claims priority to provisionalapplication Ser. No. 60/336,500 filed Oct. 24, 2001.

FIELD OF THE INVENTION

This invention relates to filling materials for use in filling dentalcavities and for root canal treatments.

BACKGROUND OF THE INVENTION

Endodontics or root canal therapy is that branch of dentistry that dealswith the diseases of the dental pulp and associated tissues. One aspectof endodontics comprises the treatment of infected root canals, theremoval of diseased pulp tissues, followed by the biomechanicalmodification and the subsequent filling of the pulp cavity (root canal).Root canal therapy is generally indicated for teeth having soundexternal structures but having diseased, dead or dying pulp tissues.Such teeth may or may not generally possess intact enamel and dentin andare satisfactorily engaged with bony tissue. In such teeth, the pulptissue and excised portions of the root should be replaced by abiocompatible substitute. One technique for the preparation of a rootcanal involves creating a coronal access opening with a conventionaldental drill. A tool is used for gross removal of pulp material from theroot canal through the coronal access opening. The void formed isenlarged with reamers and/or files to result in a fully excavatedcavity. Debris is removed from this cavity by flushing and the cavity iscleansed to remove all diseased tissue. Following chemical antisepsis,the excavated canal is ready for filling.

A basic method involves inserting a filling cone into a root canal andcementing therein to obturate the canal. The common root canal fillingcone material is made from gutta percha. Lateral condensation is amethod in which several filling cones, a primary cone and auxiliarycones, are inserted into a root canal. The primary cone is inserted andcemented to the seat of the root canal. Using a tapered spreader, theprimary cone is then squeezed against the side of the root canal and asecond cone is inserted and cemented into place. This process iscontinued until the root canal is completely obturated which can requireup to 10 to 15 filling cones. Vertical condensation of warm or hot guttapercha is yet another method of sealing root canals. After cementing aprimary cone short of the apex of the root canal, heat application isalternated with a series of smaller and smaller pluggers until the guttapercha is moved to the apex. This is often possible when the smallestplugger approaches the apex of the tooth within 3 to 5 millimeters. Thespace is then backfilled. Lateral canals are packed and sealed as aconsequence of lateral expansion of a wave of heated gutta percha.Alternatively, small segments of gutta percha can be used in this methodthat are inserted into the root canal, heated in order that they canadhere to one another and each backfilled one at a time until the rootcanal is filled. All three of these methods, the single filling cone,lateral condensation and vertical condensation apply root canal cementor sealer around the individual cones or in between segments as abinding agent.

Another method employs an injection gun that injects warm or hot guttapercha filling material into a root canal. The injector initially placesheated gutta percha at the apical area of the root canal through aneedle-like canula tip and fills the gutta percha into any surroundingvoids/spaces under pressure or at the seat of the root canal which isthen condensed with a plugger into the root tip. The injector thenbackfills the root canal by injecting additional gutta percha into theroot canal until it is obturated. A similar method involves heatinggutta percha on a flexible metal or plastic carrier used to insert thegutta percha into the root canal. The carrier may be a solid rod, or ahollow rod, situated in the center of a master cone. The rod isconnected to a handle which may be removed by slipping it out of thehollow rod, or cutting it off if it is a solid rod.

Most of the current methods employed in obturating a canal use a guttapercha material that is inert in nature and will not be absorbed ordegraded by the living tissue if the root canal is overfilled andextends beyond the apex. It has been a challenge for dentists to controlthe exact amount of the material within the border of the root canal toavoid overfilling. Moreover, gutta percha material is a polyisoprenerubber material in nature, which does not have the capability to bond tomost of the dental materials, especially when the root canal sealer is apolymer-based material. Gutta percha exhibits poor strength andbrittleness. Dental gutta percha points/cones tend to break in harshconditions, e.g., sharply curved root canals, tight spaces during a rootcanal treatment, and the like.

It is desirable to provide a root canal filling material that bondseasily to sealants. It is preferable that the root canal fillingmaterial have proper strength and flexibility. It would be beneficialthat the cavity filling material and root canal filling material bebioactive.

SUMMARY OF THE INVENTION

These and other objects and advantages are accomplished by the fillingmaterial of the present invention comprising a thermoplastic polymer.The thermoplastic polymer is preferably a biodegradable polymer. Abioactive substance may be combined with the biodegradable thermoplasticpolymer. The thermoplastic polymer acts as a matrix for the bioactivesubstance. The composition may include other polymeric resins, fillers,plasticizers, adhesives and other additives typically used in dentalfiller materials.

The filling material is used for the filling of dental cavities or rootcanals. The material may be placed in a root canal that has been openedto a predetermined dimension by use of endodontic files, to seal theapical end. If necessary, the filling material can be compacted towardthe apex, while it is still in the softened state, to ensure the apex isadequately sealed. If, by chance, the filling material is pushedslightly past the apex, or seeps through the apex, or comes in contactwith fluids in the mouth, the biodegradable material will disintegrateor break down and be absorbed or partially absorbed by the surroundingliving tissues. If a bioactive substance is present in the fillingmaterial, it will react with the tissue in the mouth, mending and/orgrowing tissue to fill in any gaps or openings.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of the present invention are disclosed in the accompanyingdrawings, wherein similar reference characters denote similar elementsthroughout the several views, and wherein:

FIG. 1 is an elevational view of an appliance having a filling materialthereon.

FIG. 2 is an elevational view of a post as an alternate carrier inaccordance with the invention;

FIG. 3 is an elevational view of an alternate embodiment of an alternatecarrier in accordance with the invention; and

FIG. 4 is an elevational view of yet another alternative embodiment ofthe invention.

DESCRIPTION OF THE INVENTION

As will be appreciated, the present invention provides a fillingmaterial for root canals and cavities comprising a thermoplasticpolymer. The thermoplastic polymer may be biodegradable. A bioactivesubstance may be combined with the biodegradable thermoplastic polymer.The thermoplastic polymer acts as a matrix for the bioactive substance.The composition may include other polymeric resins, fillers,plasticizers, adhesives and other additives typically used in dentalfiller materials including, but not limited to, antibiotic, cariostatic,antibacterial, or other anti-inflammatory, biologically active,therapeutic materials, pigments and dyes. The composition may also beuseful for root canal sealants, implants and pulp capping materials.

It is important that the thermoplastic polymer bonds well to the rootcanal sealant that is applied to the root canal. The bond strength ofthe thermoplastic polymer to the root canal sealant is equal to orgreater than about 3 MPa, and preferably equal to or greater than about4 MPa and most preferably equal to or greater than about 5 MPa.

Suitable thermoplastic polymers for use as the matrix arepharmaceutically compatible and biodegradable by cellular action and/orby the action of body fluids. Examples of appropriate thermoplasticpolymers include but are not limited to polylactides, polyglycolides,polycaprolactones, polyanhydrides, polyamides, polyurethanes,polyesteramides, polyorthoesters, polydioxanones, polyacetals,polyketals, polycarbonates, polyorthocarbonates, polyphosphazenes,polyhydroxybutyrates, polyhydroxyvalerates, polyalkylene oxalates,polyalkylene succinates, polyethylene oxides,polyacrylates/methacrylates, poly(malic acid) polymers, polymaleicanhydrides, poly(methylvinyl) ethers, poly(amino acids), chitin,chitosan, and copolymers, terpolymers, or combinations or mixtures ofthe above materials.

Preferred materials are the polylactides, polyglycolides,polycaprolactones, and copolymers thereof. These polymers can be used toadvantage in the polymer system in part because they show excellentbiocompatibility. They produce little, if any, tissue irritation,inflammation, necrosis, or toxicity. In the presence of water, thesepolymers produce lactic, glycolic, and hydroxycaproic acid,respectively, which are readily metabolized by the body. Thepolylactides and polycaprolactones can also incorporate glycolidemonomer to enhance the resulting polymer's degradation. Thebiodegradable thermoplastic polymer may be present in an amount fromabout 10 to about 100 percent by weight.

The bioactive material may include any substance or metabolic precursorthereof, which is capable of promoting growth and survival of cells,tissues, and bone. Suitable bone growth promoting substances include butare not limited to bioactive glass such as Bioglass® available from U.S.Biomaterials Corp. Alachua, Fla. calcium phosphate, Portland cement,hydroxyapatite, tricalcium phosphate, a di—or polyphosphonic acid, ananti-estrogen, a sodium fluoride preparation, a substance having aphosphate to calcium ratio similar to natural bone, calcium hydroxide,other suitable calcium-containing compounds, and the like. A bone growthpromoting substance may be in the form of a particulate or fiber fillerin nano, micro or macro form, or mixtures thereof, bone chips, bonecrystals or mineral fractions of bone and/or teeth, a synthetichydroxyapatite, or other suitable form. The bioactive filler may bepresent in an amount of up to about 90 percent by weight.

The biodegradable thermoplastic polymers should have meltingtemperatures of about 50 to about 300° C., preferably about 60 to about250° C., and most preferably about 70 to about 200° C. The meltingtemperature of the polymers in these ranges facilitates the process ofcompounding the thermoplastic polymer with bioactive inorganicparticulates and other additives. Furthermore, the melting temperaturerange of the polymers also facilitates the application of the fillingmaterial made from the compounds into a root canal with conventionalaccessible heating methods.

Examples of additional polymeric resins useful in the fillingcomposition include, but are not limited to, polyamides, polyester,polyolefins, polyimides, polyarylates, polyurethanes, vinyl esters orepoxy-based materials, styrenes, styrene acrylonitriles, ABS polymers,polysulfones, polyacetals, polycarbonates, polyphenylene sulfides,polyarylsulfides, acrylonitrile-butadiene-styrene copolymers,polyurethane dimethacrylates (hereinafter abbreviated to “UDMA”),triethylene glycol dimethacrylate (hereinafter abbreviated “TEGDMA”),polyethylene glycol dimethacrylate (hereinafter abbreviated “PEGDMA”),urethane dimethacrylate (hereinafter abbreviated “UDMA”), hexane dioldimethacrylate (hereinafter abbreviated “1,6 HDDMA”) and polycarbonatedimethacrylate (hereinafter abbreviated “PCDMA”) and the like. Among theexamples given, the resins containing surface functional groups such asacrylate/methacrylate, epoxy, hydroxyl and others are preferred sincethey not only serve as plasticizers for the compositions but as adhesivecomponents as well for promoting the bonding between the compound and asealant. Preferred polymeric matrix materials include those based onacrylic and methacrylic monomers, for example those disclosed in U.S.Pat. Nos. 3,066,112, 3,179,623, and 3,194,784 to Bowen; U.S. Pat. Nos.3,751,399 and 3,926,906 to Lee et al.; and commonly assigned U.S. Pat.Nos. 5,276,068 to Waknine (which are herein incorporated by reference).An especially preferred methacrylate monomer is the condensation productof bisphenol A and glycidyl methacrylate,2,2′-bis[4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane(hereinafter abbreviated “BIS-GMA”).

Other fillers which may be used in addition to the bioactive materialinclude inorganic and organic particulates and fibrous fillers known inthe art including, but are not limited to, silica, silicate glass,quartz, zinc oxide, barium sulfate, barium silicate, strontium silicate,barium borosilicate, strontium borosilicate, borosilicate, lithiumsilicate, amorphous silica, bismuth compounds such as BiOCl, ammoniatedor deammoniated calcium phosphate and alumina, zirconia, tin oxide, andtitania, among other conventional fillers such as those disclosed incommonly assigned U.S. Pat. Nos. 4,544,359 and 4,547,531 to Waknine(which are incorporated herein by reference). Some of the fillers alsoact as radiopaque/high refractive index materials, such as apatites,silica glass fillers, calcium silicate based fillers, hydroxyapatites,barium sulfate and bismuth subcarbonate. Fibrous fillers also include,but are not limited to, include glass, ceramic, metal, carbon, graphite,polymeric such as cellulose, polyamide, aramid, polyester, polyaramid,acrylic, vinyl and modacrylic, polyolefin, polytetrafluorethylene,mixtures thereof, as well as other fibers known in the art. The fibersmay be of uniform or random length, unidirectional or multidirectional,or randomly dispersed, and may be as short as about 3 to about 4millimeters (mm) or shorter. The fibers may also be in the form offabric as set forth in U.S. Pat. No. 6,186,791, or as possiblereinforcing fibers, as used in U.S. Pat. Nos. 4,717,341 and 4,894,012 toGoldberg et al., all of which are hereby incorporated by reference.

Examples of plasticizers useful in the filling composition include, butare not limited to, polyol, polyolfin or a mixture thereof. Theplasticizer can be incorporated into the composition in the range of upto about 90 percent by weight if other additives are not included and upto about 40 percent by weight, preferably up to about 30 percent byweight, and most preferably up to about 20 percent by weight if otheradditives are included. Examples of adhesives useful in the fillingcomposition include, but are not limited to, acrylate, methacrylate, ora mixture thereof.

The following examples illustrate the invention.

EXAMPLE 1

A composition comprising polycaprolactone available from Union Carbidein an amount of about 40%, a bioactive glass having a compositionsimilar to Bioglass™ (available from by U.S. Biomaterials) in an amountof about 30%, USP grade zinc oxide in an amount of about 20% and bariumsulfate as a radio-opacifying agent in an amount of about 10% wasmanufactured. The method of forming the composition involved heating thepolycaprolactone at about 70° C. to a softened state. The remainingingredients were then added and mixed under the action of kneading,pressing, or mixing to blend into the polycaprolactone completely toform a homogenous dough. The formed compound was then ready forapplication to the carrier device.

EXAMPLE 2

A composition comprising polycaprolactone in an amount of about 30%,caprolactone (methacryloxy)ethyl ester (CMEE) in an amount of about 10%,tricalcium phosphate in an amount of about 30%, and zirconium oxide inan amount of about 10% was manufactured. The method of forming thecomposition involved heating the polycaprolactone (available from UnionCarbide) at about 70° C. to a softened state. The remaining ingredientswere then added and mixed under the action of kneading, pressing, ormixing to blend into the polycaprolactone completely to form ahomogenous dough. The formed compound was then ready for application tothe carrier device.

The following Table 1 sets forth examples of the filling materialcompositions made similar to the methods described in Examples 1 and 2above.

TABLE 1 Composition WEIGHT (%) A B C D E P767* 40 30 21 25 P787* 9 27PEGDMA(400) 5 8 UDMA 10 CMEE** 10 Bioactive glass 30 10 21.5 30 ZnO 2010 21.5 25 25 BaSO₄ 20 22 20 BiOCl 10 Ca(OH)₂ 20 Ca₃(PO₄)₂ 20 ZrO₂ 10*P767 and P787 are polycaprolactone resins sold under the trade name ofTONE ™ POLYMER by Dow Chemical Co. **CMEE is caprolactone (methacryloxy)ethyl ester

The compositions were then prepared for bonding strength tests asfollows:

Sample Preparation for Bonding Tests

The compositions from Table 1 above were softened at about 80° C. in aconvection oven. While the materials were at a workable consistency,they were placed in 15 mm diameter and 1.2 mm thickness steel moldsbetween two glass slides and were cooled down to bench temperature.Sample disks were formed and the glass slides and molds were removed.Some trimming was necessary to remove the flashes from the edge. Fivediscs were prepared for each test material.

The sample disks were then mounted into a cold-cured acrylic mountingmaterial in a splitable cylindrical TEFLON™ mold of a 20 mm diameter andabout a 30 mm height, leaving one side of the disk exposed. Atwo-component self curable A2 shaded Cement-It™ C&B Universal Cement(Pentron Corp., Wallingford, Conn.), which is a methacrylate resincement, was used to make a composite button and was bonded directly tothe exposed sample surfaces. Number five (#5) Gelatin capsules (TorpacInc. NJ) were used to load the cement and were placed directly onto thesurfaces under a load of 500 grams on a Bencor testing device (DenvilleEngineering, CA) until the cement hardened. The cement has a settingtime of approximately 4 minutes after the two components are mixed.After one hour of bench setting, the bonded samples were debonded with apush shear mold in a Bencor test device under a crosshead speed of 0.02in/minute. The maximum load at which the cement cylinders broke from thesample surfaces was recorded. Bonding strengths were calculated usingthe load divided by the contact surface area of the cement cylinder.

The following Table 2 sets forth bonding strengths of the fillingcompositions in Table 1 along with a gutta percha composition forcomparison.

TABLE 2 Compositions Bond Strength, MPa (S.D.) A 3.2 (1.1) B 5.5 (2.3) C6.5 (1.9) D 6.8 (0.7) E 6.8 (1.2) Gutta Percha Control* 0 (Samples allfailed before testing) *The control is a dental gutta percha materialavailable from Endodent, Inc. Duart, CA

Transverse Deflection Tests

To test the flexibility of the compositions herein, a testing apparatusfor the transverse deflection test as described in ADA specificationNumber 12 for Denture Base Polymers was adopted for the test. The testsamples were made into bars of 50×3×3 mm in a TEFLON splitable moldwhile the materials were at a soft stage. A 500 gram weight was appliedonto the center of the test sample through the loading nose. The spanbetween the two supports was 30 mm. The still load was removed after oneminute (if the sample had not broken during the standing period) and themaximum deflection distance was measured and recorded. Three testsamples were run for each test material. The test results are shown inTable 3.

TABLE 3 Maximum Deflection Time of Test Samples Compositions Distance(mm) withstanding the load) A 6–8 Full minute without break C 7–9 Fullminute without break Gutta Percha 1–3 1–2 seconds (Broke almost Controlinstantly after applied the load)

The results of the inventive materials are shown to have superiorresults over the gutta percha material.

The bioactive material can be miscible in the polymer to provide ahomogeneous mixture with the polymer, or insoluble in the polymer toform a suspension or dispersion with the polymer. The filling materialmay be in the form of a cone to be inserted into a canal. The cone maybe inserted into the canal using a file or similar instrument, or it maybe attached to a file, shaft or similar carrier which instrument is theninserted into the canal with the cone thereon. After insertion, thecarrier is removed or the excess of the cone is cut off as in aconventional gutta percha cone application from the root canal.

Alternatively, the material may be softened and compacted toward theapex, while it is still in the softened state, to ensure the apex isadequately sealed. This may be done by a backfilling technique whereby,for example, the material is heated and injected into the canal using adevice having a needle, such as the Obtura II device available fromObtura/Spartan, Fenton, Mo.

If, by chance, the filling material is pushed slightly past the apex, orseeps through the apex, or comes in contact with fluids in the mouth,the biodegradable material will disintegrate or break down and beabsorbed or partially absorbed by the surrounding living tissues and thebioactive substance present in the filling material will react withtissue in the mouth, mending and/or growing tissue to fill any gaps oropenings.

Commonly assigned U.S. Pat. No. 6,455,608 is directed to dentalcompositions comprising degradable polymers for use as root canalsealants, implants and pulp capping materials and is hereby incorporatedby reference. The compositions use polymerizable and degradablemacromonomers to provide precursors for forming biodegradable andbiocompatible polymers upon a chemical reaction, which advantageouslyallow for tissue regrowth.

As yet another alternative, the filling material may be integrallyformed on a post whereby a single post unit comprises a combinedendodontic post and tip of filling material. To use the post unit, thetip of the device is softened by placing in an oven or heater to heatand soften the filling material or chemically treating to soften thematerial. The device will then be placed in a root canal that has beenopened to a predetermined dimension by use of endodontic files, to sealthe apical end. If necessary, the filling material can be compactedtoward the apex, while it is still in the softened state, to ensure theapex is adequately sealed. The post may then be cemented into place bylining the canal walls with a bonding agent and filling the interfacebetween the post and the walls of the canal with a resin cement such asa dual cure cement, a light cure cement or a self cure cement such asFiberFill™ RCS root canal sealant or Cement-It® Universal cement, bothavailable from Pentron Clinical Technologies, LLC in Wallingford, Conn.This will result in a coronal seal of the canal via a resin restorativematerial and an apical seal of the canal by means of a filling materialand sealant. The remaining portion of the post, extendingsupra-gingivally, will be used to build a core around it. Any excesswill be cut off. One length of the device will be longer to accommodatethe longer roots in anterior teeth. Another length will be shorter toaccommodate smaller roots in the molar region. Various diameters mayalso be provided to accommodate the different sizes of root canals. Thebonded flexible post may strengthen the tooth to prevent subsequent rootfractures.

Reference is made to FIGS. 1 through 4 which show carriers having thefilling material applied to the tip of the carrier. FIG. 1 shows anappliance 10 having a handle 12 and an elongated shaft 14. Shaft 14 hasa proximal end 14 p and a distal end 14 d that fits in a root canal. Asliding support 16 is positioned between shaft 14 and handle 12 to serveas an indicator of the depth of the canal and to help maintain thecarrier in place. After the appliance is inserted in the canal, slidingsupport 16 is moved to the point at the top of the canal. Fillingmaterial 18, containing a biodegrable thermoplastic polymer and abioactive filler, is positioned on the shaft, starting at the proximalend and continuing down, over the distal end.

Turning to FIG. 2, a post unit 20 is shown comprising a post section 21and a cone or tip section 24. Tip section 24 comprises a flexible rod orcone comprising a biodegrable thermoplastic polymer in combination witha bioactive substance for filling the apex of the canal. The fillingmaterial may include additives typical in the dental field such asplasticizing, antibiotic, cariostatic, antibacterial, or otheranti-inflammatory, biologically active or therapeutic materials.

Post section 21 comprises a main body or endodontic portion 22 and acarrier or apical portion 23 which is located at the apical end of postunit 20. Main body 22 may be a solid rod of circular or other suitablecross-section comprising a substantially smooth surface or may comprisea plurality of frustoconical sections arranged coaxially along thelongitudinal axis of main body 22. Preferably, main body 22 hasconsistent width along the longitudinal axis thereof whereasfrustoconical sections each have the same tapered width and same length.It is possible to vary the width and/or length of main body 22 and/orvary the tapered width and/or length of frustoconical sections along thelongitudinal axis of main body 22.

Carrier 23 is preferably an extension of main body 22 of post section 21and is of very fine diameter to accommodate tip section 24 ofthermoplastic material of post unit 20. In one method of manufacturewhich will be discussed hereinafter, post section 21 is manufacturedfrom a rod of material that is cut or machined at the apical end toresult in carrier 23 having a very small width or diameter in comparisonto main body 22. Carrier 23 is of small diameter to allow enough area toform tip section 24 thereon, and also of enough strength and integrityto accommodate the filling material as discussed above. As stated above,carrier 23 is preferably an extension of main body 22 and is shownhaving constant diameter along the length thereof, but may be of anyshape or size sufficient to hold tip section 24 thereon. Post section 21may be fabricated of any material to provide a flexible apical portionand a more rigid endodontic and/or coronal or supracoronal portion, suchas metal, plastic, ceramic, polymeric, composite, or other materialsuitable for placement in the mouth. Composite materials include but arenot limited to filler reinforced composite materials and fiberreinforced composite materials comprising the reinforcing component in apolymeric matrix material such as those composite materials listed inU.S. Pat. Nos. 4,717,341 and 4,894,012 to Goldberg et al., U.S. Pat. No.6,039,569 to Prasad et al., U.S. Pat. No. 6,030,220 to Karmaker et al,U.S. Pat. No. 5,564,929 to Alpert, and U.S. Pat. No. 5,919,044 toSicurelli, Jr. et al., all of which are hereby incorporated byreference. The fiber reinforced composite material may comprise fibersin the form of long, unidirectional, continuous filaments which arepreferably at least partially aligned and oriented along thelongitudinal dimension of the component with alignment normal orperpendicular to that dimension also possible. The fibers may be ofuniform or random length, unidirectional or multidirectional, orrandomly dispersed, and may be as short as about 3 to about 4millimeters (mm) or shorter. The fibers may also be in the form offabric as set forth in copending Ser. No. 09/280,760 filed Mar. 29,1999, now U.S. Pat. No. 6,186,791, and may include any of the attributesof the post described therein, the contents all of which are herebyincorporated by reference. Due to the improved structural integrity, theamount of fibers in the structural component preferably equals at leastabout 20% by weight (wt %) and preferably about 20 wt % to about 70 wt%. Possible reinforcing fibers, which are preferably used in accordancewith U.S. Pat. Nos. 4,717,341 and 4,894,012 to Goldberg et al. (whichare herein incorporated by reference), include glass, ceramic, metal,carbon, graphite, polymeric such as cellulose, polyamide, aramid,polyester, polyaramid, acrylic, vinyl and modacrylic, polyolefin,polytetrafluorethylene, mixtures thereof, as well as other fibers knownin the art. One preferred version of the device is comprised ofunidirectional microfilamentous glass fibers bundled in a resin matrix.

In order to enhance the bond between the fibers and polymeric matrix,thereby enhancing the reinforcing effect, the fibers may be silanized orotherwise treated such as by grafting functional monomers to obtainproper coupling between the fibers and the resin matrix. Silanizationrenders the fibers hydrophobic, reducing the water sorption andimproving the hydrolytic stability of the composite material, rendersthe fibers organophilic, improving wetting and mixing, and bonds thefibers to the polymeric matrix. Typical silane is A-174 (p-methacrylatepropyl tri-methoxy silane), produced by OSI Specialties, New York.

The polymeric matrix is selected from those known in the art of dentalmaterials, including, but not limited to, polyamides, polyester,polyolefins, polyimides, polyarylates, polyurethanes, vinyl esters orepoxy-based materials, styrenes, styrene acrylonitriles, ABS polymers,polysulfones, polyacetals, polycarbonates, polyphenylene sulfides,polyarylsulfides, acrylonitrile-butadiene-styrene copolymers,polyurethane dimethacrylates (hereinafter abbreviated to PUDMA), and thelike. Preferred polymeric matrix materials include those based onacrylic and methacrylic monomers, for example those disclosed in U.S.Pat. Nos. 3,066,112, 3,179,623, and 3,194,784 to Bowen; U.S. Pat. Nos.3,751,399 and 3,926,906 to Lee et al.; and commonly assigned U.S. Pat.Nos. 5,276,068 to Waknine (which are herein incorporated by reference).An especially preferred methacrylate monomer is the condensation productof bisphenol A and glycidyl methacrylate,2,2′-bis[4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane(hereinafter abbreviated “BIS-GMA”).

The polymer matrix, which typically includes polymerization initiators,polymerization accelerators, ultra-violet light absorbers,anti-oxidants, fluorescent whitening agents, free radical initiators,and/or other additives well known in the art, may be visible lightcurable, self-curing, dual curing, or vacuum, heat, or pressure curablecompositions, as well as any combination thereof. Heat and pressure orvacuum curable compositions include a heat cure initiator such asbenzoyl peroxide, 1,1′-azobis(cyclohexanecarbo-nitrile) or other freeradical initiators. The preferred polymeric matrix is a light and heatcurable matrix, wherein light effects partial cure of the polymermatrix, while final curing is by heat under controlled atmosphere.

Fillers may be present in addition to or instead of fibers in an amountup to about 80 wt %, and preferably about 70 wt %. If fibers arepresent, the amount of filler is present in an amount of up to about 30wt % of one or more fillers known in the art and used in dentalrestorative materials. Suitable fillers include those capable of beingcovalently bonded to the polymeric matrix itself or to a coupling agentthat is covalently bonded to both. Fillers include silica, silicateglass, quartz, barium silicate, strontium silicate, barium borosilicate,strontium borosilicate, borosilicate, lithium silicate, amorphoussilica, ammoniated or deammoniated calcium phosphate and alumina,zirconia, tin oxide, and titania, among other conventional fillers suchas those disclosed in commonly assigned U.S. Pat. Nos. 4,544,359 and4,547,531 to Waknine (which are incorporated herein by reference), whilepossible coupling agents include silanes, zirconates, and titanates. Ifthe post is manufactured from a composite material, it is preferably incompletely cured or hardened state.

Examples of metals useful as post section 21 include but are not limitedto metals or alloys of Pd, Pt, Rh, Ir, Au, Ag, Ti, Co, Mo and mixturesthereof such as AgPd, AuPtPd, TiAlFe, TiAlV,CoCrMo, stainless steel andbrass. Ceramic materials useful in the fabrication of post section 21include but are not limited to alumina, zirconia, mullite, spinel,porcelain, titania, lithium disilicate, leucite, amorphous glass,lithium phosphate, and combinations thereof, or any high strengthceramic material which can withstand the stresses created in the mouth.

Carrier 23 preferably comprises a smooth surface, although it is in noway limited to such and may be of any surface suitable for applicationof filling material thereon. The post may be provided in an opaque toothcolor or it may be colored similar to a tooth's pulp for enhancedesthetics. The post may include an appropriate amount of radiopaquematerial such as titanium oxide, barium sulfate, and similar materialsknown in the dental industry to insure x-ray documentation which may beadded to the post material during manufacture thereof. After postsection 21 has been manufactured, carrier 23 of post section 21 is thencoated with a filling material such as set forth above to obtain conesection 24 thereon. The filling material may be applied by any knownmeans such as dipping, injection molding, hand rolling, and the like.

To use the post unit, the device may be used as is, or may be heated byplacing in or near an oven or heater to heat and soften the fillingmaterial or dipped in a chemical solution such as chloroform to softenthe filling material. The device will then be placed in a root canalthat has been opened to a predetermined dimension by use of endodonticfiles, to seal the apical end. If necessary, the filling material can becompacted toward the apex, while it is still in the softened state, toensure the apex is adequately sealed. The post is then cemented intoplace by lining the canal walls with a bonding agent and filling theinterface between the post and the walls of the canal with a resincement, such as a dual cure cement. This will result in a coronal sealof the canal via resin restorative material and an apical seal of thecanal by means of filling material and sealant. The remaining portion ofthe post, extending supra-gingivally, will be used to build a corearound it, and if necessary, for placement of a crown thereon. Anyexcess of the post will be cut off. One length of the device will belonger to accommodate the longer roots in anterior teeth. Another lengthwill be shorter to accommodate smaller roots in the molar region.

FIG. 3 shows a post unit 30 comprises a post section 32 fabricated offiber reinforced composite material. Post section 32 includes main body34 and carrier 36. Carrier 36 is coated with a filling material toobtain cone section 38 thereon. As shown in the drawing, main body 34 istapered to provide ease of placement into the canal. The cross-sectionof post unit 30 may be smaller than the cross-section of a standard postto fit in thinner or smaller auxiliary canals which are normally filledwith a thermoplastic material. Accordingly, post unit 30 can act as anobturator. As an obturator, better support is provided due to thefiber-reinforced composite structural component 34 upon which conesection 38 is applied in comparison to using only a thermoplasticmaterial as an obturator. Moreover, the obturator may be easily cementedin place in the canal. Post unit 30 may also include a handle 40 whichis beneficial when the post unit is used as an obturator. Handle 40 maybe any filled or unfilled polymeric material, such as those mentionedabove and used in the fabrication of the post.

FIG. 4 is directed to an obturator 40 having filling core or point 42and a handle 44. Filling core 42 is a shaft 46 having a proximal end 46p and a distal end 46 d that fits in a root canal. A sliding support 48is positioned between shaft 46 and handle 44 to serve as an indicator ofthe depth of the canal and to help maintain the obturator in place.After the appliance is inserted in the canal, sliding support 48 ismoved to the point at the top of the canal. Obturator 40 is cut off atthe point desired to fit the canal. Filling core 42 containing abiodegrable thermoplastic polymer and optionally, a bioactive filler, inthe form of shaft 46, fills the canal. The filling core 42 and handle 44are a single unit fabricated of a biodegradable thermoplastic polymerand optionally, a bioactive filler. Alternatively, the filling core ismade of a biodegradable thermoplastic polymer and optionally, abioactive filler and the handle may be fabricated of any know materialincluding but not limited to metal, plastic, composite, ceramic, glassor polymeric material.

The compositions of the inventive materials have a radiopacity similarto gutta percha materials.

While various descriptions of the present invention are described above,it should be understood that the various features can be used singly orin any combination thereof. Therefore, this invention is not to belimited to only the specifically preferred embodiments depicted herein.Further, it should be understood that variations and modificationswithin the spirit and scope of the invention may occur to those skilledin the art to which the invention pertains. Accordingly, all expedientmodifications readily attainable by one versed in the art from thedisclosure set forth herein that are within the scope and spirit of thepresent invention are to be included as further embodiments of thepresent invention. The scope of the present invention is accordinglydefined as set forth in the appended claims.

1. A filling material for cavities and root canals comprising: athermoplastic polymer matrix and an adhesive; and optionally, abioactive filler; wherein the filling material has a bond strength whenbonded to a root canal sealant equal to or greater than about 3 MPa; andwherein the filling material cannot be mixed, kneaded, or pressed atroom temperature.
 2. The filling material of claim 1 wherein thethermoplastic polymer matrix comprises a biodegradable polymer.
 3. Thefilling material of claim 1 wherein the thermoplastic polymer matrix ispresent in an amount from about 10 percent to about 100 percent byweight.
 4. The filling material of claim 1 wherein the bioactive filleris present in an amount of up to about 90 percent by weight.
 5. Thefilling material of claim 2 wherein the biodegradable polymer comprisespolylactides, polyglycolides, polycaprolactones, polyanhydrides,polyamides, polyurethanes, polyesteramides, polyorthoesters,polydioxanones, polyacetals, polyketals, polycarbonates,polyorthocarbonates, polyphosphazenes, polyhydroxybutyrates,polyhydroxyvalerates, polyalkylene oxalates, polyethylene oxides,polyacrylates/methacrylates, polyalkylene succinates, poly(malic acid)polymers, polymaleic anhydrides, poly(methylvinyl) ethers, poly(aminoacids), chitin, chitosan, and copolymers, terpolymers, or combinationsor mixtures thereof.
 6. The filling material of claim 1 wherein thebioactive filler comprises bioactive glass, calcium phosphate, Portlandcement, hydroxyapatite, tricalcium phosphate, a di- or polyphosphonicacid, an anti-estrogen, a sodium fluoride preparation, a substancehaving a phosphate to calcium ratio similar to natural bone, or mixturesthereof.
 7. The filling material of claim 1 wherein the bioactive fillercomprises bone chips, bone crystals, mineral fractions of bone or teeth,or mixtures thereof.
 8. The filling material of claim 1 wherein thebioactive filler comprises particulate or fibrous filler in nanosize,microsize, macrosize form, or mixtures thereof.
 9. The filling materialof claim 1 further comprising a plasticizer.
 10. The filling material ofclaim 9 wherein the plasticizer is present in an amount of up to about90 percent by weight.
 11. The filling material of claim 9 wherein theplasticizer comprises polyol, polyolfin or a mixture thereof.
 12. Thefilling material of claim 1 wherein the adhesive comprises an acrylate,methacrylate, epoxy or hydroxyl component, or a mixture thereof.
 13. Thefilling material of claim 1 further comprising a polymeric resin,additional filler, pigment, dye, antibiotic, cariostatic, antibacterial,anti-inflammatory, biologically active or therapeutic material.
 14. Thefilling material of claim 13 wherein the polymeric resin comprisespolyamides, polyesters, polyolefins, polyimides, polyarylates,polyurethanes, vinyl esters epoxy-based materials, styrenes, styreneacrylonitriles, ABS polymers, polysulfones, polyacetals, polycarbonates,polyphenylene sulfides, polyarylsulfides, polyurethane dimethacrylates,triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,urethane dimethacrylate, hexane diol dimethacrylate, polycarbonatedimethacrylate, the condensation product of bisphenol A and glycidylmethacrylate, 2,2′-bis [4-(3 -methacryloxy-2-hydroxypropoxy)-phenyl]-propane and mixtures thereof.
 15. The filling materialof claim 14 wherein the ABS polymers compriseacrylonitrile-butadiene-styrene copolymers.
 16. The filling material ofclaim 13 wherein the additional filler comprises a radiopacifyingfiller.
 17. The filing material of claim 13 wherein the additionalfiller comprises silica, silicate glass, quartz, zinc oxide, bariumsulfate, barium silicate, strontium silicate, barium borosilicate,strontium borosilicate, borosilicate, lithium silicate, bismuthcompounds, ammoniated or deammoniated calcium phosphate, alumina,zirconia, tin oxide, titania, apatites, calcium silicate based fillers,bismuth subcarbonate or mixtures thereof.
 18. The filling material ofclaim 17 wherein the bismuth compounds comprise BiOCl.
 19. The fillingmaterial of claim 17 wherein the silica comprises amorphous silica,silica glass fillers or mixture thereof.
 20. The filling material ofclaim 13 wherein the additional filler comprises a fibrous filler. 21.The filling material of claim 20 wherein the fibrous filler comprisesglass, ceramic, metal, carbon, graphite, or polymeric fibers.
 22. Thefilling material of claim 21 wherein the polymeric fibers comprisecellulose, polyamide, aramid, polyester, polyaramid, acrylic, vinyl,modacrylic, polyolefin, polytetrafluorethylene, or mixtures thereof. 23.The filling material of claim 1 shaped in the form of a cone.
 24. Anappliance for applying a filling material to a root canal of a toothcomprising: a handle; a shaft; and filling material disposed on theshaft, wherein the filling material comprises a thermoplastic polymermatrix and an adhesive, and wherein the filling material has a bondstrength when bonded to a root canal sealant equal to or greater thanabout 3 MPa; and optionally, a bioactive filler.
 25. The appliance ofclaim 24 wherein the thermoplastic polymer matrix comprises abiodegradable thermoplastic polymer.
 26. The appliance of claim 25wherein the biodegradable thermoplastic polymer comprises polylactides,polyglycolides, polycaprolactones, polyanhydrides, polyamides,polyurethanes, polyesteramides, polyorthoesters, polydioxanones,polyacetals, polyketals, polycarbonates, polyorthocarbonates,polyphosphazenes, polyhydroxybutyrates, polyhydroxyvalerates,polyalkylene oxalates, polyethylene oxides, polyacrylates/methacrylates,polyalkylene succinates, poly(malic acid) polymers, polymaleicanhydrides, poly(methylvinyl) ethers, poly(amino acids), chitin,chitosan, and copolymers, terpolymers, or combinations or mixturesthereof.
 27. The appliance of claim 24 wherein the bioactive fillercomprises bioactive glass, calcium phosphate, Portland cement,hydroxyapatite, tricalcium phosphate, a di- or polyphosphonic acid, ananti-estrogen, a sodium fluoride preparation, a substance having aphosphate to calcium ratio similar to natural bone, or mixtures thereof.28. The appliance of claim 24 wherein the adhesive comprises anacrylate, methacrylate, epoxy or hydroxyl component, or a mixturethereof.
 29. A method for restoring the root canal of a toothcomprising: preparing the root canal; applying a sealant to the walls ofthe root canal; inserting a filling material into the canal, wherein thefilling material comprises a thermoplastic polymer matrix and anadhesive and optionally, a bioactive filler; and wherein the fillingmaterial bonds to the sealant at a bond strength equal to or greaterthan about 3 MPa.
 30. The method of claim 29 wherein the thermoplasticpolymer matrix comprises a biodegradable thermoplastic polymer.
 31. Themethod of claim 30 wherein the biodegradable thermoplastic polymercomprises polylactides, polyglycolides, polycaprolactones,polyanhydrides, polyamides, polyurethanes, polyesteramides,polyorthoesters, polydioxanones, polyacetals, polyketals,polycarbonates, polyorthocarbonates, polyphosphazenes,polyhydroxybutyrates, polyhydroxyvalerates, polyalkylene oxalates,polyethylene oxides, polyacrylates/methacrylates, polyalkylenesuccinates, poly(malic acid) polymers, polymaleic anhydrides,poly(methylvinyl) ethers, poly(amino acids), chitin, chitosan, andcopolymers, terpolymers, or combinations or mixtures thereof.
 32. Themethod of claim 29 wherein the bioactive filler comprises bioactiveglass, calcium phosphate, Portland cement, hydroxyapatite, tricalciumphosphate, a di- or polyphosphonic acid, an anti-estrogen, a sodiumfluoride preparation, a substance having a phosphate to calcium ratiosimilar to natural bone, or mixtures thereof.
 33. The method of claim 29wherein the filling material further comprises a plasticizer.
 34. Themethod of claim 33 wherein root canal wherein the plasticizer comprisespolyol, polyolefin or a mixture thereof.
 35. The method of claim 29wherein the adhesive comprises an acrylate, methacrylate, epoxy orhydroxyl component, or a mixture thereof.
 36. The method of claim 29wherein filling material further comprises a polymeric resin, filler,pigment, dye, antibiotic, cariostatic, antibacterial, anti-inflammatory,biologically active or therapeutic material.
 37. The method of claim 29further comprising softening the filling material and injecting thefilling material through a needle into the canal.
 38. A filling materialfor cavities and root canals comprising: a thermoplastic polymer matrixand an adhesive, wherein the filling material has a bond strength whenbonded to a root canal sealant equal to or greater than about 3 MPa; andoptionally, a bioactive filler; wherein the thermoplastic polymer is abiodegradable polymer selected from the group consisting ofpolylactides, polyglycolides, polycaprolactones, polyanhydrides,polyamides, polyurethanes, polyesteramides, polyorthoesters,polydioxanones, polyacetals, polyketals, polycarbonates,polyorthocarbonates, polyphosphazenes, polyhydroxybutyrates,polyhydroxyvalerates, polyalkylene oxalates, polyethylene oxides,polyacrylates/methacrylates, polyalkylene succinates, poly(malic acid)polymers, polymaleic anhydrides, poly(methylvinyl) ethers, poly(aminoacids), chitin, chitosan, and copolymers, terpolymers, and combinationsthereof; and wherein the bioactive filler is selected from the groupconsisting of bioactive glass, calcium phosphate, Portland cement,hydroxyapatite, tricalcium phosphate, a di- or polyphosphonic acid, ananti-estrogen, a sodium fluoride preparation, a substance having aphosphate to calcium ratio similar to natural bone, and mixturesthereof.
 39. The filling material of claim 38 wherein the adhesivecomprises an acrylate, methacrylate, epoxy or hydroxyl component, or amixture thereof.
 40. A filling material for cavities and root canalscomprising: a thermoplastic polymer matrix, an adhesive and aplasticizer; and optionally, a bioactive filler; and wherein the fillingmaterial has a bond strength when bonded to a root canal sealant equalto or greater than about 3 MPa.
 41. The filling material of claim 40wherein the plasticizer is present in an amount of up to about 90percent by weight.
 42. The filling material of claim 40 wherein theplasticizer comprises polyol, polyolfin or a mixture thereof.